Text 563, 215 rader
Skriven 2004-10-28 16:46:00 av Michael Ragland (1:278/230)
Ärende: Quantum Theory of Big Ban
=================================



Comment to Moderator: This is relevent to the group and evolution since
I'm employing the weak anthropic principle:)

[moderator's humph: Humph! We go to great pains to point out that
abiogenesis and evolution are two distinct topics, and here you
guys are mushing them all up together. Cosmology really isn't
relevant, so let's try to keep it hooked up to evolution. - JAH]


Note: This article is over two years old and I have no idea if Hawking
and Hertog's ideas have been modified since then. Supposedly Hawking has
flip flopped on the anthopic principle since Wikipedia stated a 2004
publication by him based on quantum wave function demonstrated the Big
Bang came out of nothing and there was nothing to predetermine what it
would expand into. According to Wikipedia this was a blow to those who
subscribe to the anthropic principle and consider human life "special".
Here Hawking states, "The top-down approach is a mathematical
formulation of the Weak Anthropic Principle," Hawking writes, in which
observed values of all physical and cosmological quantities are
restricted by the requirement that carbon-based life must exist."
There is nothing necessarily contradictory between Hawking's 2004
publication Wikipedia cites and his statement here, "The top-down
approach is a mathematical formulation of the weak anthropic principle
and that observed values of all physical and cosmological quantities are
restricted by the requirement that carbon-based life must exist."
Assuming Hawking's quantum wave function theory of the Big Bang is
accurate and came out of nothing and there was nothing predetermined
obviously doesn't cancel out carbon based life in the universe. Duh!

I found this article easy to digest in layman's terms. What fascinated
me the most was the top-down versus the bottom up physics approach to
the Big Bang. According to Hawking, "The usual approach to the problem
of initial conditions for inflation is to assume some initial
configuration for the universe and evolve it forward in time," Hawking
said. "This could be described as the 'bottom up' approach to
cosmology." The top-down approach is described by Hawking as, "The
quantum origin of our universe implies one must take a 'top down'
approach to the problem of initial conditions in cosmology," Hawking and
Hertog write in their latest paper on the subject – "Why does
inflation start at the top of the hill?"    

They explain, "Inflation – and creation – started at the top of a
potential energy mountain, the two cosmologists claim, where fundamental
field particles acted like snowflakes that coalesced into cosmological
snowballs. A rolling stone may gather no moss, but the rolling die of
creation – known to physicists as a subatomic particle called the
"Hawking-Moss instanton" – gathered these snowflake-like particles.
I'm aware there are apparently problems with the Hawking-Moss instanton
theory. 

The article goes on, "Like mischievous children, quantum fluctuations in
the early universe rolled the cosmological snowball down the hill and it
expanded. Because of Heisenberg's famous uncertainty principle, the
field at the top of the hill fluctuates," Hertog explained. "Because the
top of the hill is an unstable point, these fluctuations eventually
cause the field to roll all the way down." 

Hertog states, "The snowball of creation eventually settled into a
valley and became the universe that surrounds us today. Although this
valley is lower than it was at the beginning of everything, "the bottom
of the valley doesn't seem to be at sea level," Hertog said.
Cosmological sea level may be described by Einstein's famous
"cosmological constant that cosmologists are measuring," he added. 
Hawking and Hertog assert that their "top down" approach to cosmology is
a fundamental departure from scientific tradition.

Here is what I found on Einstein's cosmological constant:

A constant  introduced by Einstein  (1917) into the equations of general
relativity to allow a steady state cosmological solution to the Einstein
field equations. The constant was introduced before the concept of the
Big Bang had been conceived, so an expanding or contracting universe
was regarded as physically implausible, leading Einstein to add  as a
"fudge factor." In theory, the constant can be derived from quantum
field theory, but the derivation has not yet been performed. Einstein's
cosmological constant is equivalent to a vacuum energy density, which
means it can be put on the left hand side of Einstein's equations with
the geometry (as Einstein did), or on the right hand side with the
stress-energy, both forms being mathematically equivalent. 
Generally,  does not play a significant role in the early universe.  
Big Bang, Cosmology, Einstein Field Equations 
 
References  
Einstein, A. "Kosmologische Betrachtungen zur allgemeinen
Relativitätstheorie." Sitzungsber. Preuss. Akad. Wiss., 142-152, 1917.
Reprinted in English in Lorentz, H. A.; Einstein, A.; Minkowski, H.;
and Weyl, H. The Principle of Relativity: A Collection of Original
Memoirs on the Special and General Theory of Relativity. New York:
Dover, 1952. 
Goldsmith, D. Einstein's Greatest Blunder? The Cosmological Constant and
Other Fudge Factors in the Physics of the Universe. Cambridge, MA:
Harvard University Press, 1997. 
Ridpath, I. (Ed.). A Dictionary of Astronomy. Oxford, England: Oxford
University Press, 1998. 
Weinberg, S. Gravitation and Cosmology: Principles and Applications of
the General Theory of Relativity. New York: Wiley, p. 613, 1972. 
© Eric W. Weisstein 
 
My question is if our universe did originate in a Big Bang and will
ultimately collapse does Einstein's cosmological constant still
theoretically be derived from quantum field theory? Does a steady state
cosmological solution jibe with Einstein's equations? Everywhere it is
referred to as the "fudge factor". This was apparently the case even
before the Big Bang model came about or the theory of a collapsing
universe. There seems to be something in Einstein's equations which go
against a cosmological constant.

Michael Ragland
 


Hawking: God may play dice after all
WorldNetDaily ^  | May 23, 2002 | By Mike Martin
Posted on 05/23/2002 3:02:41 AM PDT by lavaroise

Despite an aging Albert Einstein's famous comment, "God does not play
dice with the universe," renowned cosmologist Stephen Hawking and his
academic collaborator Thomas Hertog now suggest that God did roll the
dice at least once – at the moment of creation. 

Like that familiar wizened sage atop the highest peak, God cast that
first die down a mountain of potential energy where, according to
Hawking and Hertog, it rolled like a snowball, growing, expanding and
inflating into the universe we know today. 

"The quantum origin of our universe implies one must take a 'top down'
approach to the problem of initial conditions in cosmology," Hawking and
Hertog write in their latest paper on the subject – "Why does
inflation start at the top of the hill?" 
Inflation – and creation – started at the top of a potential energy
mountain, the two cosmologists claim, where fundamental field particles
acted like snowflakes that coalesced into cosmological snowballs. A
rolling stone may gather no moss, but the rolling die of creation –
known to physicists as a subatomic particle called the "Hawking-Moss
instanton" – gathered these snowflake-like particles.
 

"The early evolution of our universe is a bit like a ball of snow that
grows while rolling down a hill," Hertog told WorldNetDaily in an
exclusive interview. Hertog equated the growing snowball to a field of
particles. "Our calculations show that our universe was most likely
created by this field at the top of a 'potential hill.'" 

Like mischievous children, quantum fluctuations in the early universe
rolled the cosmological snowball down the hill and it expanded. 
"Because of Heisenberg's famous uncertainty principle, the field at the
top of the hill fluctuates," Hertog explained. "Because the top of the
hill is an unstable point, these fluctuations eventually cause the field
to roll all the way down." 

The snowball of creation eventually settled into a valley and became the
universe that surrounds us today, Hertog explained. Although this valley
is lower than it was at the beginning of everything, "the bottom of the
valley doesn't seem to be at sea level," Hertog said. Cosmological sea
level may be described by Einstein's famous "cosmological constant that
cosmologists are measuring," he added. 
Hawking and Hertog assert that their "top down" approach to cosmology is
a fundamental departure from scientific tradition. 

"The usual approach to the problem of initial conditions for inflation
is to assume some initial configuration for the universe and evolve it
forward in time," Hawking said. "This could be described as the 'bottom
up' approach to cosmology." 

The quantum nature of the cosmos, however, dictates the "top down"
approach, Hawking claims, because the history of the universe depends on
the mountain, the dice, the snowflakes and the snowballs. In other
words, the universe "depends on the observables being measured." 

God may play dice then, but only if the dice are loaded. If the universe
depends on observables, it also depends on we the observers, so the dice
had to somehow guarantee that we humans would emerge. 
Physicists call this idea the so-called "Weak Anthropic Principle" from
the Greek "anthropos," which means "man" or "human." 

"The top-down approach is a mathematical formulation of the Weak
Anthropic Principle," Hawking writes, in which observed values of all
physical and cosmological quantities are restricted by the requirement
that carbon-based life must exist. 

"The top-down approach incorporates the Weak Anthropic Principle because
it takes into account certain observed features of our universe – such
as the fact that it expands – in order to explain its origin," Hertog
said. "In other words, a top down approach does not tell us how the
universe should be, but why the universe is the way it is." 

"If Hawking speaks, we should probably listen," Randolph-Macon College
physics professor George Spagna told WorldNetDaily from Ashland, Va. 

"The approach Hawking and Hertog apply in their paper is to work
backwards from the current state of the universe to its possible
origins, rather than attempting to cook up the appropriate initial state
and see if it evolves forward into something resembling the present
universe," Spagna explained. "Hence, it is akin to attaching mathematics
to the Weak Anthropic Principle, because we obviously inhabit a universe
whose conditions permit our very existence in the first place." 

Mike Martin regularly reports on breaking science news for
ScienceNewsWeek, United Press International and other publications. View
his other stories at sciencenewsweek.com.

"Tiny green men might have been a better experiment."

Stephen Hawking
(paraphrasing from a "Universe in a Nutshell".
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